Trophic level index

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The trophic level index (TLI) is used in New Zealand as a measure of nutrient status of lakes.[1] It is similar to the trophic state index but was proposed as alternative that suited New Zealand.[2]

The system uses four criteria, phosphorus and nitrogen concentrations, as well as visual clarity and algal biomass weighted equally.[3]

Lake type Trophic level Chla (mg m−3) Secchi depth (m) TP (mg P m−3) TN (mg N m−3)
Ultra-microtrophic 0-1 0.13-0.33 31-24 0.84-1.8 16-34
Microtrophic 1-2 0.33-0.82 24-15 1.8-4.1 34-73
Oligotrophic 2-3 0.82-2.0 15-7.8 4.1-9.0 73-157
Mesotrophic 3-4 2.0-5.0 7.8-3.6 9.0-20 157-337
Eutrophic 4-5 5.0-12 3.6-1.6 20-43 337-725
Supertrophic 5-6 12-31 1.6-0.7 43-96 725-1558
Hypertrophic 6-7 >31 <0.7 >96 >1558

See also

External links

  • New Zealand Ministry for the Environment - Trophic Level Index for lakes
  • Definitions of the 5 trophic states - Oligotrophic, Mesotrophic, Eutrophic, Supertrophic and Hypertrophic lakes

References

  1. ^ New Zealand Ministry for the Environment Archived 2010-05-22 at the Wayback Machine. - Trophic Level Index for lakes
  2. ^ Burns, Noel; Graham Bryers; Eddie Bowman (March 2000). Protocol for Monitoring Trophic Levels of New Zealand Lakes and Reservoirs. Retrieved 2017-05-09.
  3. ^ Burns, Noel; McIntosh, John; Scholes, Paul (2005). "Strategies for Managing the Lakes of the Rotorua District, New Zealand". Lake and Reservoir Management. 21 (1): 61–72. doi:10.1080/07438140509354413.


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